1. Field of the Invention
The present invention relates to a two-finger micromanipulator for use in biotechnology, medicine, and various industrial fields in which micromanipulation is required.
2. Description of the Prior Art
In JPB Hei 6-104308 one of the present inventors proposed a microhand having two fingers for manipulating minute objects. The basic configuration of this two-finger microhand is as shown in FIG. 4. The two-finger hand employs a pair of hand modules 100 utilizing parallel linkages with six degrees of freedom. Each of the hand modules 100 has a base plate 101 and a base member 104 with a finger 102. The base plate 101 and base member 104 are connected by six spring links 105. The six links 105 are divided into two groups of three each. The links of both groups are connected with the base plate 101 and base member 104 at points uniformly spaced along circles whose centers are the axial centers of the base plate 101 and base member 104, but with the links of one group inclined in the opposite direction from those of the other group. Each of the links 105 is provided with an actuator that extends and contracts the links 105.
A problem with this arrangement is that, since the links 105 are held between the base plate 101 and the base member 104 by spring force, the micromanipulator is liable to break down structurally when exposed to an external force exceeding the spring force. Another problem is that the micromanipulator is unable to follow rapid movements.
To overcome these problems, in U.S. Pat. No. 5,476,357 one of the inventors proposed using flexible metal wire members at each end of the six links 105 to connect the links with the base member 104 and base plate 101. This eliminated the problems that arise from the use of springs. However, it is difficult to control the hand modules 100 with the high level of coordination required to manipulate minute objects. A further problem is that the hand modules 100 have only a small operating range.
The fingers resemble chopsticks. Observation of the way a person uses chopsticks shows that interlocking motions of the whole hand are used, with fine manipulations done by the chopstick moved by the index finger and the other chopstick held steady. Based on these observations, it is desirable to divide the functions of the above microhand so that the finger corresponding to the index finger chopstick is controlled for mainly fine gripping operations by producing fine, relative motions, while the finger corresponding to the other chopstick is mainly used for positioning over a large operational space. This enables the shortcomings of the conventional micromanipulator arrangements to be resolved.
The present invention was achieved in light of the foregoing findings and has as its object to provide a two-finger micromanipulator that enables objects to be readily manipulated within a large operating region by fine relative motions that are easy to control.
A further object of the present invention is to provide a two-finger micromanipulator that enables objects to be readily manipulated using a simple mechanism, comprising an upper parallel linkage for driving micromanipulator fingers to make mainly fine relative motions, and a lower parallel linkage mainly for positioning in a large operating space.